Your picture of the nitro thinner dedomed SST-40 next to the toluene dedomed SST-40 shows exactly why we should use toluene.
The greenish tint is all to familiar to chemical dedomers, we all want the other result (right one in the picture).
Also, the fact that a tough dome like SST-40 is gone after a short while, and without heating the solvent, is another reason to get pure toluene.
This could also be because of different C8 hosts. I couldnāt completely screw the bezel down on the Toluene one. So it might just be different focus.
Edit: Iāll swap the mcpcb in both host and check if it makes a difference on the hotspot.
Yeah, that is weird. But as far as I know everyone else who uses nitro thinner gets the green tint shift. Do you boil the liquid? Does yours contain acetone?
What do you mean by tint shift is nearly invisible? Does it still turn slightly green?
Wish you show us and explain your procedure little better. Can you Show result of your hot/cold nitro de doming vs toulene ( photo of both de domed emitters).
It seems that you discover something new and good and community will be grateful if you reveal your method. If you can show us photo of your method. I really looking forward to it.
IME when you take the dome to the bare phosphor no matter which method tint shift will happenā¦
I had similar results with hot dedome(2 methods of this hot de doming, there are 90% chance of leaving silicone residue on emitter after that methods and yes that will lead to less tint shift(tint shift still happens) cause there are still some silicone remains sticked to emitter phosphor surface). Solvent methods take all that silicone to the bare phosphor and they maybe even recycle micro particles of phoshor so yes there is probably a chance for even greater tint shift.
So your toulene method takes all the silicone to the bare phosphor but tint shift almost did not happened? Hmmā¦ Well It could beā¦
My guess that toulene leaves some silicone residues on phosphor. Or how to say it canāt dissolve the part of the silicone that is merged with emitter phosphor surface. And if that happens it is goodā¦ Real goodā¦ Can you please show us results with photo?
Iām about to do that, just havenāt had the time to do it todayā¦ But I donāt have a specific procedure yet as Iāve only done it once with toluene. It could just be a fluke, even though I donāt think so.
And as you said, if it leaves a tiny bit of the silicone over the phosphorus I donāt mind. I happily sacrifice a bit of throw for a tint without green.
Good question! I didnāt clean it at all, just let it dry. After every other dedome I rinsed with isopropyl alcohol and theyāve turned out bad. So Iāve been a little suspicious that this could be part of the green shift.
Even the LEDs that I didnāt dedome but cleaned with isopropyl seem to have worse tint than the ones that Iāve never cleaned.
I was thinking that if you just pull it out of the solvent and let it dry, itāll still have a microscopically thin coat of silicone once the remaining solvent dries. By rinsing it with IPA, youāre making sure to rinse off everything.
Hmmā¦ I swapped the LEDs between the two hosts because I had a better driver in the one that has green tint. Guess what happened? The perfect white sst-40 is now green and the other one now has no green in itā¦
I donāt understand a thingā¦ Could it be the driver that causes the tint shift? Thatās the only explanation I have now.
One of the driver is a FET only with PWM and that one is the one that donāt have the tint shift.
LEDs ran on PWM will always display their tint at their maximum current IIRC, because of how the PWM worksā¦ My SST-40 gives me a brilliant cool white with little green at max output, but at lower outputs on a non PWM driver, it gets rather green.
Just thinking out loud. I know that Mitko and 18sixfifty uses FET only drivers and coincidentally they are two of the members that have reported that they dedome without tint shift. Could it be that easy?
No, everything is the same, two identical hosts. Both have AR-lens and to be perfectly sure I tried them without reflector and lens. It made no difference. Iām quite positive that it is because of the FET only.